I'm using mosfets drivers such as IR2112 for a BLDC motor, now each driver should be given a PWM signal on low side and high side, I would have 3 low sides and 3 high side. What PWM signal should be given through microcontroller(6 PWM signals).(BLDC motor do have HALL effect sensors). I have to write a code but I'm confused about PWM.

 

It's not just as simple as writing some PWM code. You need to understand what's going on in a BLDC motor with Hall sensors too. Take some time and read this application note for an old IC that explains what is going on with driving a Hall sensored BLDC, then see if you can write a code to do it. Better than just assuming PWM is all that's needed.

https://www.onsemi.com/download/application-notes/pdf/an1046-d.pdf

 

Have you looked at some of the modern BLDC drive IC's such as the L6235 etc?
Takes care of the commutation also.
https://www.homemade-circuits.com/50v-3-phase-bldc-motor-driver-circuit/